prevalent will depend not so much on the degree and rate of crowding i the constitution (both genetic and experiential) of the population and Lature of physical and biological agents to which the population is, or has , exposed. .nally, if the harmful effects of crowding on health are to be prevented an orderly and healthful rate of population growth to be planned, the jsses through which crowding is related to health need to be understood r than they are today. As indicated earlier, the relatively simplistic no-that crowding exerts its deleterious effects solely through facilitating the personal spread of disease agents is no longer adequate to explain the /n phenomena. A more appropriate formulation would seem feasible if ecognize that increased population density increases the importance of ocial environment as a determinant of physiological response to various ili, including potentially disease-producing agents; that within this social onment the quality of social interactions and position within the group to be important factors; and that, given time, adaptation to these social ges can and does occur, but the newcomers to the situation will always te segment of the population at highest risk. REFERENCES faylor, Ian, and John Knowelden, Principles of Epidemiology. Boston: Little, Brown, and Co., 1957. p. 199. Vital Statistics of the United States, 1939-40 Supplement. Washington: Dept. of Health, Education, and Welfare. Vital Statistics of the United States, 1950. Washington: Bureau of the Census, 1964. Vol. III. Statistical Abstract of the United States. Washington: Bureau of the Census, 1964. Vital Statistics of the United States, 1960. Washington: Bureau of the Census, 1963. Vol. II. Vital Statistics of the United States, 1966. Washington: Bureau of the Census, 1968. Vol. II. Author's calculations of Linear Projections of Population Changes, 1950-1960. DuBos, Rene, "The Human Environment in Technological Societies," The Rockefeller Foundation, 1968. pp. 1-11. The Registrar General's Decennial Supplement England and Wales, 1961, Area Mortality Tables. London: Her Majesty's Stationery Office, 1967. Shapiro, Sam, et al., Infant, Perinatal, Maternal, and Childhood Mortality in the United States. Vital and Statistical Monographs APHA. Harvard Univ. Press, 1968. Dauer, Carl C., et al., Infectious Diseases. Vital and Statistical Monographs APHA. Cambridge, Mass.: Harvard Univ. Press, 1968.y determine the ability of the population to adapt successfully to the new situation, and the degree to which new types of social groups can develop to fulfill the function originally played by the family and kinship group will in large part determine how deleterious such changes are.